1. Field of the Invention
The present invention relates to electronic equipment, and a restriction removal method using electronic equipment. More particularly, the present invention relates to electronic equipment for removing restriction on activation of a machine tool, and a restriction removal method for removing restriction on activation of a machine tool.
2. Description of the Background Art
Conventionally, systems for restricting activation of machine tools upon relocation of the machine tools in order to prohibit illegal use thereof (hereinafter referred to as “relocation sensing systems”) are known.
Japanese Patent Laying-Open No. 2008-129706 discloses an activation restriction system for a machine tool as the relocation sensing system. This activation restriction system detects an installation position of a machine tool by using a GPS, and restricts activation or function of the machine tool if the detected installation position is beyond a previously registered allowable area.
On the other hand, if relocation sensed by the relocation sensing system is based on legal use, restriction on activation of a machine tool needs to be removed. In order to remove the restriction on activation imposed by the relocation sensing system, a unique removal code needs to be input to each machine tool. The removal code may be leaked during removal of the restriction on activation, however.
Japanese Patent Laying-Open No. 2009-251694 discloses a technique of using a removal code which is unique to each one of numerical control devices mounted on a machine tool and is only enabled for a predetermined number of times, for the numerical control devices. As a result, security during removal of restriction on activation is improved in Japanese Patent Laying-Open No. 2009-251694.
Japanese Patent Laying-Open No. 2010-3210 discloses a system for recovering a function of a numerical control device having the function of preventing relocation of a machine. Installation position information and an allowable movement distance are input to and stored in an FROM (Flash Read Only Memory) in the numerical control device via an input device. In this system, position information is input to the numerical control device from a GPS (Global Positioning System) unit via a GPS interface, and the position information is stored in a SRAM (Static Random Access Memory) in the numerical control device. A processor in the numerical control device reads a program stored in the FROM, and calculates a movement distance based on the position information and the installation position information. The processor determines whether or not the calculated movement distance is within a range of allowable movement distance, and if the movement distance is within the range of allowable movement distance, performs function recovery processing on the numerical control device.
With mere determination of whether or not the movement distance is within the allowable movement distance in the above configuration of the system in Japanese Patent Laying-Open No. 2010-3210, however, illegal position information on the GPS unit may be input. In order to prevent such illegal input, this system sets an allowable time based on time elapsed since detection of the position information with the GPS unit, and determines whether or not to transmit the position information from the GPS unit to the numerical control device.